[Darwin] MTRDevice _reattemptSubscriptionNowIfNeededWithReason needs to be called while holding lock (project-chip#37710)

Author: jtung-apple

src/darwin/Framework/CHIP/MTRDevice_Concrete.mm

@@ -1072,6 +1072,7 @@ - (void)_triggerResubscribeWithReason:(NSString *)reason nodeLikelyReachable:(BO
     // The subscription reattempt here eventually asyncs onto the matter queue for session,
     // and should be called after the above ReleaseSession call, to avoid churn.
     if (shouldReattemptSubscription) {
+        std::lock_guard lock(_lock);
         [self _reattemptSubscriptionNowIfNeededWithReason:reason];
     }
 }